Mercurial > hg
view mercurial/formatter.py @ 29322:66dbdd3cc2b9 stable
bdiff: extend matches across popular lines
For very large diffs that have large numbers of identical lines (JSON
dumps) that also have large blocks of identical text, bdiff could become
confused about which block matches which because it can only match
very limited regions. The result is very large diffs for small sets of edits.
The earlier recursion rebalancing fix made this behavior more frequent because
it's now more prone to match block 1 to block 2. One frequent user of
large JSON files reported being unable to pass the resulting diffs
through their code review system.
Prior to this change, bdiff would calculate the length of a match at
(i, j) as 1 + length found at (i-1, j-1). With large number of popular
(ignored) lines, this often meant matches couldn't be extended
backwards at all and thus all matching regions were very small.
Disabling the popularity threshold is not an option because it brings
back quadratic behavior.
Instead, we extend a match backwards until we either found a previously
discovered match or we find a mismatching line. This thus successfully
bridges over any popular lines inside and before a matching region.
The larger regions then significant reduce the probability of confusion.
author | Matt Mackall <mpm@selenic.com> |
---|---|
date | Thu, 02 Jun 2016 17:09:06 -0500 |
parents | d813132ea361 |
children | b501579147f1 |
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# formatter.py - generic output formatting for mercurial # # Copyright 2012 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import cPickle import os from .i18n import _ from .node import ( hex, short, ) from . import ( encoding, error, templater, ) class baseformatter(object): def __init__(self, ui, topic, opts): self._ui = ui self._topic = topic self._style = opts.get("style") self._template = opts.get("template") self._item = None # function to convert node to string suitable for this output self.hexfunc = hex def __nonzero__(self): '''return False if we're not doing real templating so we can skip extra work''' return True def _showitem(self): '''show a formatted item once all data is collected''' pass def startitem(self): '''begin an item in the format list''' if self._item is not None: self._showitem() self._item = {} def data(self, **data): '''insert data into item that's not shown in default output''' self._item.update(data) def write(self, fields, deftext, *fielddata, **opts): '''do default text output while assigning data to item''' fieldkeys = fields.split() assert len(fieldkeys) == len(fielddata) self._item.update(zip(fieldkeys, fielddata)) def condwrite(self, cond, fields, deftext, *fielddata, **opts): '''do conditional write (primarily for plain formatter)''' fieldkeys = fields.split() assert len(fieldkeys) == len(fielddata) self._item.update(zip(fieldkeys, fielddata)) def plain(self, text, **opts): '''show raw text for non-templated mode''' pass def end(self): '''end output for the formatter''' if self._item is not None: self._showitem() class plainformatter(baseformatter): '''the default text output scheme''' def __init__(self, ui, topic, opts): baseformatter.__init__(self, ui, topic, opts) if ui.debugflag: self.hexfunc = hex else: self.hexfunc = short def __nonzero__(self): return False def startitem(self): pass def data(self, **data): pass def write(self, fields, deftext, *fielddata, **opts): self._ui.write(deftext % fielddata, **opts) def condwrite(self, cond, fields, deftext, *fielddata, **opts): '''do conditional write''' if cond: self._ui.write(deftext % fielddata, **opts) def plain(self, text, **opts): self._ui.write(text, **opts) def end(self): pass class debugformatter(baseformatter): def __init__(self, ui, topic, opts): baseformatter.__init__(self, ui, topic, opts) self._ui.write("%s = [\n" % self._topic) def _showitem(self): self._ui.write(" " + repr(self._item) + ",\n") def end(self): baseformatter.end(self) self._ui.write("]\n") class pickleformatter(baseformatter): def __init__(self, ui, topic, opts): baseformatter.__init__(self, ui, topic, opts) self._data = [] def _showitem(self): self._data.append(self._item) def end(self): baseformatter.end(self) self._ui.write(cPickle.dumps(self._data)) def _jsonifyobj(v): if isinstance(v, tuple): return '[' + ', '.join(_jsonifyobj(e) for e in v) + ']' elif v is None: return 'null' elif v is True: return 'true' elif v is False: return 'false' elif isinstance(v, (int, float)): return str(v) else: return '"%s"' % encoding.jsonescape(v) class jsonformatter(baseformatter): def __init__(self, ui, topic, opts): baseformatter.__init__(self, ui, topic, opts) self._ui.write("[") self._ui._first = True def _showitem(self): if self._ui._first: self._ui._first = False else: self._ui.write(",") self._ui.write("\n {\n") first = True for k, v in sorted(self._item.items()): if first: first = False else: self._ui.write(",\n") self._ui.write(' "%s": %s' % (k, _jsonifyobj(v))) self._ui.write("\n }") def end(self): baseformatter.end(self) self._ui.write("\n]\n") class templateformatter(baseformatter): def __init__(self, ui, topic, opts): baseformatter.__init__(self, ui, topic, opts) self._topic = topic self._t = gettemplater(ui, topic, opts.get('template', '')) def _showitem(self): g = self._t(self._topic, ui=self._ui, **self._item) self._ui.write(templater.stringify(g)) def lookuptemplate(ui, topic, tmpl): # looks like a literal template? if '{' in tmpl: return tmpl, None # perhaps a stock style? if not os.path.split(tmpl)[0]: mapname = (templater.templatepath('map-cmdline.' + tmpl) or templater.templatepath(tmpl)) if mapname and os.path.isfile(mapname): return None, mapname # perhaps it's a reference to [templates] t = ui.config('templates', tmpl) if t: return templater.unquotestring(t), None if tmpl == 'list': ui.write(_("available styles: %s\n") % templater.stylelist()) raise error.Abort(_("specify a template")) # perhaps it's a path to a map or a template if ('/' in tmpl or '\\' in tmpl) and os.path.isfile(tmpl): # is it a mapfile for a style? if os.path.basename(tmpl).startswith("map-"): return None, os.path.realpath(tmpl) tmpl = open(tmpl).read() return tmpl, None # constant string? return tmpl, None def gettemplater(ui, topic, spec): tmpl, mapfile = lookuptemplate(ui, topic, spec) assert not (tmpl and mapfile) if mapfile: return templater.templater.frommapfile(mapfile) return maketemplater(ui, topic, tmpl) def maketemplater(ui, topic, tmpl, filters=None, cache=None): """Create a templater from a string template 'tmpl'""" aliases = ui.configitems('templatealias') t = templater.templater(filters=filters, cache=cache, aliases=aliases) if tmpl: t.cache[topic] = tmpl return t def formatter(ui, topic, opts): template = opts.get("template", "") if template == "json": return jsonformatter(ui, topic, opts) elif template == "pickle": return pickleformatter(ui, topic, opts) elif template == "debug": return debugformatter(ui, topic, opts) elif template != "": return templateformatter(ui, topic, opts) # developer config: ui.formatdebug elif ui.configbool('ui', 'formatdebug'): return debugformatter(ui, topic, opts) # deprecated config: ui.formatjson elif ui.configbool('ui', 'formatjson'): return jsonformatter(ui, topic, opts) return plainformatter(ui, topic, opts)